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Iranian crab apple 'Zinati' with dual tolerance as maternal source selected for rootstock breeding

Hajnajari, H., Soroori, S., Rezaei, S., Zadeh, H. Zamani
Acta horticulturae 2012 no.938 pp. 527-534
Phytophthora cactorum, apples, breeding, crown rot, experimental design, genes, genotype, germination, orchards, powdery mildew, relative humidity, rootstocks, seedlings, seeds
Great part of Iranian soils present heavy physical texture, calcareous and chemical alkaline nature. The most diffused clonal rootstock MM106 in Iranian orchards shows frequently susceptibility to crown rot disease. Iranian selected apple crabs ‘Morabbaei’ from two different origins Kamalabad (Karaj-Alborz) and Isfahan province, ‘Zinati’, ‘Azayesh’ and imported ‘Northern Spy’ known as carrier of resistance gene to Phytophthora cactorum the agent of crown rot disease. 5 groups of the relative open pollinated seeds were collected in addition to 'Northern Spy' to assess intro - inter varietal tolerance to P. cactorum in the respective young seedlings obtained from selected dwarf apple rootstocks, all classified by specific codes, in 2007-2009. Germination percent was calculated in each family. Young Off springs were maintained in thermostatic green house at 20±1°C, ≥ 90% relative humidity after inoculation to Phytophthora cactorum. Damage level was recorded every 3 days for 4 consecutive months. Green intensity and seedling’s height were recorded every month for 6 times. Furthermore, Level of tolerance to natural attack of powdery mildew was also estimated for all genotypes within the populations. The experimental design was applied in split plot in time. The results indicated ‘Zinati’ F1 descendents demonstrated maximum dwarfism compared to other progenies. Contemporaneously, they demonstrated high tolerance both to crown rot and powdery mildew attacks. Currently (2012), the selected genotypes are under stool bed layering to evaluate rooting potential. in the nursery.